Bloodbot Robot Takes Blood Samples

Bloodbot is a prototype robot designed to take blood samples; it identifies a suitable blood vessel by pressing a probe against the ante-cubital fossa (ACF) skin surface. and then measuring the force. The ACF is the crease of the arm where the veins are close to the skin. It was developed at Imperial College, London.

The presence of a vein is revealed in the difference in the characteristics of the tissue from its surroundings. Once a vein is found, Bloodbot inserts a needle; the force/position profile identifies the proper positioning.

The first axis moves a carriage up and down, so that it goes towards and away from the arm that is strapped in under it. This carriage is used to hold either a blunt probe (for finding a vein) or a syringe and needle. A piezo-resistive force sensor is mounted on the carriage to measure the force on the probe or needle.

The second axis moves the carriage across the width of the arm. This enables the probe to press in a series of places along the width of the arm.

The third axis, which is unpowered, enables a human operator to tilt the robot. This is so that, once a vein has been found, the needle can be inserted into the arm at the correct angle.

The fourth axis moves the whole robot along the length of the arm. This was designed to compensate for the slight difference between where the probe has identified a vein, and where the needle enters the skin, once the robot has been tilted.

Bloodbot is very close to the hypo arm from Harry Harrison's 1958 story Simulated Trainer:

...the padded arms slipped across his bunk, pinning him down securely. He watched the panel slip back in the wall next to him and the hypo arm slide through, moving erratically like a snake as its metal fingers sought him out. They touched his ankle and the serpent's tooth of the needle snapped free. The last thing he saw was the needle slipping into his vein, then the drug blacked him out.

Bloodbot has been tested on one human patient; a vein was successfully located 78% of the time. I don't have a figure on the success of human health care workers, but based on my many conversations with nurses, 78% is not bad.